Known vehicle wheels include) a two-piece wheel with a rim attached to a side surface of a disk (Japanese Utility Model Laid-Open Publication No. SHO-62-71003), a wheel with a half-split rim (Japanese Patent Laid-Open Publication No. HEI-9-20103), a two-piece wheel with a disk attached to the inside of a rim (Japanese Utility Model Laid-Open Publication No. HEI-3-55441), and a wheel of a three-piece configuration.
FIG. 10 hereof illustrates a wheel disclosed in Japanese Utility Model Publication No. SHO-62-71003. This wheel has a configuration in which a rim half 202 provided with a disk 201 and a rim half 204 provided with a disk 203 are welded together at the peripheries of the disk 201 and the disk 203. 205 denotes welds.
FIG. 11 hereof illustrates a wheel disclosed in Japanese Patent Laid-Open Publication No. HEI-9-20103. This wheel is configured with a rim 212 welded to a side surface of a disk 211. 213 denotes a weld.
FIG. 12 hereof illustrates a wheel disclosed in Japanese Utility Model Laid-Open Publication No. HEI-3-55441. This wheel is a small-diameter large-width wheel having a step 222 provided in a well 221 of a rim, a disk 223 attached to the step 222, and a plurality of mounting holes 224 provided in the disk 223 for mounting to a hub of a vehicle.
FIG. 13 hereof illustrates a wheel of a three-piece configuration. A wheel 231 consists of an inner wheel 232, an outer wheel 233, a center disk 234 interposed between the inner wheel 232 and the outer wheel 233, and a plurality of connecting members 236 for connecting those three components together and also serving as mounting parts to a hub 235. The connecting members 236 are provided with nut seats for receiving nuts 238 screwed to bolts 237 at the side of the hub 235. With the connecting members 236, the wheel 231 is centered with respect to the hub 235.
In the wheel shown in FIG. 10, the disks 201, 203 of the rim halves 202, 204 are planar. In the case of providing depressions and protrusions or decorative holes in the disks 201, 203, the disks 201, 203 should be formed to an exact shape; otherwise it becomes difficult to join the disks 201, 203 together. Accordingly, the shape of the disks 201, 203 has to be made simple. Under this, the design freedom of the disks 201, 203 is reduced.
The disk 211 shown in FIG. 11 is produced by press molding and the rim 212 is formed by roll forming. If the disk 211 and the rim 212 could be formed by the same forming method such as press molding, they could be produced by the same processing machine on the same line, resulting in improved productivity.
For the wheel shown in FIG. 12, to mount the wheel to the hub, the accuracy of the mounting holes 224 to be fitted to bolts at the hub should be improved; otherwise it becomes difficult to improve the centering accuracy of the wheel with respect to the hub. Improving the accuracy of the mounting holes 224 results in cost increase.
The wheel shown in FIG. 13 has the connecting members 236 as additional members to the other members of the wheel 231, thus having an increased number of components, and the wheel 231 has the three-piece configuration, thus resulting in an increased number of assembling steps, which leads to cost increase.